Good thing plesk added that additional comment. Because their error message is so much more informative than the default IE provides to help the user in case of uninformative error messages.
1) It's a 404 page. The main information here is "your link doesn't work". No detailed diagnostic is needed.
2) This default 404 page can be customized to match a site layout and styling and possibly have search boxes, etc. to help you find the page you were looking for. You even helpfully get a comment to let you know to keep your page code over 512 bytes.
1) the IE default page gives additional information what could cause the problem and how to maybe fix it. And it is localized to the users language. As such IE's page is much better for a non-technical user and doesn't at all impede the technical user.
2) the moment that page gets customized with all that info you propose it will be longer than the 512 bytes at which point IE will not display its customized error page.
Plesk's solution here does nothing but make life harder for non-techies (which admittedly don't use plesk) for no reason what so ever. The page served in the example is inferior to IE's page in all aspects. Hence my snarky comment
1) Not all defaults are awesome. The issue here is that this is not even a site default, this is a default for a multi-website management program.
And for that matter, if you leave the wrong settings unset on recent versions of IIS, this message won't go out anyway, since IIS will push its own default page for non-200 responses.
2) It's trivial to have a simple, CSS-based site layout that requires less than 512 bytes in the base HTML page. For a simple notice that this isn't a known page on the site, but here's a search form, you could easily still be under 512 bytes.
Your comment was like a bucket of cold water thrown in my face, snapping me out of my own smarminess in order to get back to doing something useful. Thanks.
It's a default page provided by web hosting management software. You use Plesk to manage multiple web sites, which may not be related to each other or even use similar backends (for instance, if you're a web host with multiple clients).
The people managing the code and content of the site in question are responsible for customizing their error pages.
Microsoft products are full of annoying features like this. Another example is Outlook and the way it removes arbitrary newlines from plain text emails.
Short messages are usually of the form "404 - File not Found". These are non-informative for many users ("what does it mean?"), don't give any recovery options ("what can I do now?"), and aren't localised.
Yes. That's really well done.